Networks enable computers and other devices to exchange data such as e-mail messages, web pages, audio, video, and so forth. To send data across a network, a sending device typically constructs a collection of packets. Individual packets store some portion of the data being sent. A receiver can reassemble the data into its original form after receiving the packets
Network devices receiving packets perform a wide variety of operations. For example, some devices, known as routers and switches, examine packets to determine how to forward the packet further on a path toward its destination. Other devices, known as firewalls, examine packets to identify those that may pose a security risk. Due to continuing increases in network connection speeds and the volume of network traffic, network devices perform their operations at increasing speeds.
Many different hardware and software schemes have been developed to handle packets. For example, some designs use software to program a general purpose Central Processing Unit (CPU) processor to process packets. Other designs, such as designs using components known as application-specific integrated circuits (ASICs), feature dedicated, “hard-wired” approaches.
To combine the programmable flexibility of a CPU with the speed often associated with an ASIC, many vendors sell programmable devices known as network processors. Network processors enable software programmers to quickly reprogram network processor operations. Currently, network processors can be found in a variety of network systems including routers, switches, firewalls, line cards, and storage area network (SAN) components, among others.